The present invention relates to a lens array, a lens unit, an exposure device, an LED head, and an image forming apparatus.
An electrophotographic image forming apparatus includes an LED head (i.e., an exposure device) in which a plurality of LEDs are arranged. The image forming apparatus further includes an optical system that forms erecting unmagnified images of objects in a line shape. The optical system includes a lens array in which a plurality of microlenses are arranged. Such an image forming apparatus is disclosed in, for example, Japanese Patent Application Publication No. 2008-92006 (Pages 5-6 and FIG. 1).
However, in the conventional exposure device, a beam shape may change periodically corresponding to an arrangement interval of the microlenses. In such a case, when the image forming apparatus prints an image, vertical streaks may be formed on a printed image at intervals corresponding to the arrangement interval of the microlenses.